06 F150 has a rough idle

I have a 2006 Ford 150 with about 120,000 miles on it… For almost 9 months now I’ve had a really rough idle and I can’t seem to get it to smooth out. I’ve tried new plugs, tune up, new fuel filter, higher octane gas, fuel injector cleaner, octane booster, cleaned my mass air flow sensor and nothing helps… I’ve checked the trucks ECM for any codes but it comes up clean every time… Any one got any ideas? I’m stumped…

Intake manifold gasket leak ?

So you’ve got no fault codes . . . good

Where are your fuel trims at? That should give you valuable information as to whether you have a lean condition and on what bank it is.

Did you look for clues on the old sparkplugs?

What do you mean by fuel trims? And bank??

When I changed the plugs the two that were all the way in the back had some rust on them so I changed the coil packs on those two just to be safe…

How can I check to see if the intake manifold gasket is leaking?